S: (n) Saint Lawrence Seaway, St. Lawrence Seaway (a seaway involving the Saint Lawrence River and the Great Lakes that was developed jointly by Canada and the United States; oceangoing ships can travel as far west as Lake Superior)
S: (n) crossing, crosswalk, crossover (a path (often marked) where something (as a street or railroad) can be crossed to get from one side to the other)
S: (n) lane (a well-defined track or path; for e.g. swimmers or lines of traffic)